Various mining machines, such as those of Goodman type, displace themselves among cog or rack track comprising a plurality of racks aligned longitudinally and connected together at their ends. The mining machine has a pair of sprockets over which is spanned a chain whose rollers or cross pieces engage the teeth of the racks for displacement of the mining machine.
Normally the machine is associated with an elongated trough formed of individual sections each of which is provided with a respective rack-rail section. The joints between the individual rack-rail sections are normally provided at the approximate centers of the trough sections, so as to minimize flexing and ensure the proper alignment of the rail sections.
German patent publication No. 2,530,754 (whose U.S. equivalent is U.S. Pat. No. 4,082,361) shows such a system wherein the rail sections are connected together at their ends by means of simple pins or bolts which allow limited flexing at the joints. This arrangement has the advantage of simplicity and ease of servicing, yet nonetheless normally results in considerable wear of the teeth at the ends of the rail sections. This wear is due to the fact that when the two rail sections are not perfectly aligned with each other the spacing between the two teeth immediately flanking the joint will be more or less than the spacing between the teeth offset from the joint. Thus as the mining machine travels across the joint at least one of the teeth is going to be extremely heavily loaded for a moment, resulting in damage and premature wear to the teeth.